This invention is directed to a device which extracts air from the interior of a structure and is useful during cataclysmic storms, wherein a pressure differential is created between the interior of the structure and the ambient environment. The device allows for reduction of the pressure within the interior of the structure to prevent the pressure differential within the interior of the structure from blowing the roof off of the structure. Further the device is useful for removing warm air from within the structure and ventilating the structure under normal climatic conditions.
In many areas of the world, local climatic conditions are such that storms are generated which have winds of excessive speed and force. In certain areas of the world, notably those areas where a continent is adjacent to a tropical ocean, certain large, catastrophic storms, generically referred to as tropical cyclones, occur. These tropical cyclones range in size from sixty to well over one thousand miles in diameter. Depending upon the location where these storms occur, they are known by a variety of names. The storms striking the North American Continent are commonly referred to as hurricanes, those striking the Asian Continent are commonly referred to as typhoons, and those striking the Australian Continent are commonly referred to as cyclones.
In order to be classed as a tropical cyclone, whether it be locally known as hurricane, typhoon, or cyclone, winds of generally in excess of sixty-five miles an hour must be present. Winds of less intensity are generally associated with storms referred to as tropical storms or tropical depressions.
Inhabited land masses which are subject to tropical cyclones incur large amounts of damage from passage of these storms over these land masses. The severity of the damage is, of course, in proportion to the severity of the storm, including the wind speed of the storm and the surge heighth of the waves accompanying the storms. Because of the wind forces associated with these tropical cyclones, pressure gradients are created within structures differing from the ambient pressure of the exterior environment of the structure. These pressure gradients are sometimes so severe with the tropical cyclones that it is not too uncommon for the roof of such a structure to be completely blown off.
Building codes in certain areas have been enacted to recognize the potential of these pressure gradients blowing the roof off of structures and sometimes require that the roof of the structure be engineered not only to support the downward force of the roof itself, but also be engineered to resist being blown off the structure. Unfortunately, not all areas of either the United States or the world which are subject to tropical cyclones include these building code provisions, and further, many older structures are not so engineered. As a result of this, much of the damage to structures during the passage of a tropical cyclone over an inhabited land mass includes damage to the structure because of the blowing off of the roof, and associated damage to the structure after the roof is no longer there to protect the interior of the structure.
There are many ventilating apparatus known which assist in removing hot or stale air from the interior of a structure to the ambient environment. These ventilating structures, however, are not engineered, nor designed, to withstand the extreme wind forces during a tropical cyclone, or to function in conjunction with these wind forces to dissipate the pressure within the interior of the structure. Indeed, most of the known ventilating structures simply present obstacles which are easily torn off of the structures to which they are attached by the high winds associated with the tropical cyclones. Once torn off or so removed from a structure, these free-floating devices then become dangerous solid obstacles being moved with lethal force by the winds of the tropical cyclone.